death by multimeter (idea)

Urban legend, I'm afraid. Disclaiming addendum: with most people and most multimeters! The teacher probably just didn't want you spouting blood all over the classroom and equipment.

Let's look at why:

• The heart needs about 50mA running through it to stop it.
• The average human internal resistance is a kilohm or two. Note: this is the "under-skin" resistance - if you just hold the terminals, you'll see about a megohm.
• Your typical multimeter uses a maximum of 9V to test resistance.

Using Ohm's law and a pessimistic 1000 ohms for the human, your multimeter would need to put 1000 ohms * 0.05A = 50V across its terminals.

Alternatively, for death by 9V, you'd need to have an internal resistance of 9V / 0.05A = 180 ohms

In other words, unless you're a very good conductor, you're safe.

Phssthpok - firstly, it is current, not amperage. Secondly, most multimeters test with DC, so you'd still be OK. Thirdly, the bits of the sinoatrial node that matter are small. Really small. To get 100mV potential difference across them, you'd have to apply 9V across just 90x their width, assuming homogenous resistance.